1. Field of the Invention
The present invention relates to a novel method for production of and an apparatus for encapsulation and termination of devices, including electronic or electrochemical device. The present invention provides, for example, for electrochemical devices, such as, for example, thin-film batteries with sensitive chemistries that can survive environmental exposure while providing external electrical contact to the internal cell chemistry. The method of packaging of the present invention may include bonding one or more protective multi-layer laminates to the environmentally sensitive surfaces of an electronic device. The present invention can provide the advantage of avoiding or reducing entrapped air beneath the laminates.
2. Description of the Art
One category of encapsulated electrochemical devices includes lithium-ion (“Li-ion”) batteries. One standard structure used to encapsulate solid-state Li-ion batteries incorporates a parylene/copper multi-layer. Although such structures may be somewhat impermeable under standard ambient conditions, they are poor protectors when exposed to elevated temperature and humidity. Another encapsulation method for Li-ion thin-film batteries entails the use of a multi-layer bag and a bonding adhesive or thermal plastic that is edge-sealed to produce a closed bag enclosure. In these types of enclosures the bonding adhesive or thermal plastic is the weak point. More importantly, the gas in such a sealed bag may expand at elevated temperatures resulting in a seam breach. Transport of such a sealed bag to a high altitude may create a similar risk of seam breach due to differential pressure bag expansion.
Another category of encapsulated electrochemical devices includes lithium batteries. Lithium batteries have been available with a liquid electrolyte for some time. However, lithium batteries have only recently been manufactured in a solid-state configuration. Among the challenges of producing such solid-state batteries is creating a product with a long functional life.
Thin-film batteries that contain materials like lithium that react when exposed to water or air must be thoroughly shielded or encapsulated from those environments. One such encapsulation approach is described in U.S. Pat. No. 5,561,004, wherein parylene, metal, or ceramic layer combinations are employed to produce a thin-film barrier. The parylene metal encapsulant claimed in this patent, however, is not capable of protecting cells at 85° C./85% relative humidity accelerated life testing for more than one hour. Another encapsulation approach is described in U.S. Pat. No. 6,080,508, wherein encapsulation is attempted by use of an edge-sealed multi-layer pouch with insulating strips used to protect the conductor leads from shorting through the metal layer of the pouch during final edge sealing. However, when exposed to 85° C./85% relative humidity for less than 24 hours, such encapsulant pouches tend to experience seam breakage, greatly reducing their potential utility.